Telephone-exchange system.



No. 646,697. Patented Apr. 3, I900.

- w. n. GHARKY.

TELEPHONE EXGHA NGE SYSTEM.

(Application flied m 17, 1899.)

(M Model.)

2 Sheets-Sheet l,

m: NORRIS PETERS co, PHUTOLITHOH wnsumm'on, n. c.

N0. 646,697. Patentd Apr. 3, I900.

w. n. GHARKY.

TELEPHONE EXCHANGE SYSTEM.

ga pumion filed m 17, 1899.) (No Model.) 2 Sheets-Sheet 2.

x m: mums P zrin: ea. rumours-0.. WASHINGTON. I:v c.

UNITED STATES- PATENT ()FFICE.

IVILLIAM D. GIIARKY, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE SUN ELECTRIC MANUFACTURING COMPANY, OF NEWV JERSEY.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION termite ea of Letters retent No. 646,697, dated April 3, 1906.

Application filed May 1'7, 1899. Serial No. 117,155. (No model.)

T0 001% whom it may concern.-

Be it known that I,-WILLIAM D. GHARKY, a citizen of the United States, residing in Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a certain new and useful Improvement in Telephone-Exchange Systems, of which the following is a specification, reference being had to the accompanying drawings, forming apart hereof, in which the same letters and figures of vision of means whereby a signal at the central office may be actuated to remain permae nently displayed, and yet be self-restoring upon the mere breaking of the circuit by the insertion of a plug, without constant current being supplied to the lines. In other words, it contemplates the permissible use of selfrestoring central-energy automatic signals with lines having the ordinary generator for calling.

A further object of my invention is the provision of an improved supervisorysignal.

In order to attain my objects, I provide, in the first place, a relay-magnet for each line, which may also control a display-drop whose contacts are in the circuit of a lamp-signal and also include controlling-contacts in the spring-jack. The magnet has ,double windings, one winding being to line and the other winding being included in certain local circuits which become active upon the energization of the magnet and are thereafter under the control of the operator in answering a call. My supervisory signal I locate in a grounded bridge of the cord-circuit, the ground, however, being entirely removed from the connected lines during conversation.

In the accompanying drawings,.Figure 1 is a diagrammatic representation of a central stationcontaining circuits embodying my invention together with two substations connected therewith. Fig. 2 is a similar representation of a somewhat modified system.

Referring to Fig. 1, X is one subscribers station and Y another, each connected with the central station by line-wires l 2. The apparatus of both stations consists of the same elements, which are lettered alike, so that the description of station X will apply to both. At said station I provide the usual transmitter T,- receiver R, induction I, hook-switch S, generator G, ringer Q, and local battery 25. The hook-switch S has a parallel member S connected to it by an insulated part, both members being pivoted so that they travel together under the weight of the receiver in one direction and by means of a suitable springin the other direction. The two switch members S S are connected to the line-wires 1 and 2, respectively, and when the receiver is upon the hook they serve, by resting upon the usual local circuit together with the primary winding 11 of the induction-coil I and the local battery it, the continuity of such circuit being controlled primarily by the switch S through the contacts 5 In addition to this control, however, I employ a gravity-switch S whose function will be explained in connection with the central-office apparatus and the use of which is fully set forth in my prior patent, No. 620,440, issued February 28, 1899. The switch S cooperates with the contact 8 to make or break the local circuit without af from one extremity through wire 12 to another spring 9' in the jack, which normally rests, as shown, against the extremity of a twin springj which is connected by wire 11 to a contact a, adapted to cooperate with armature at of magnet A, the armature in turn being connected by wire 17 to bus-bar 20 of the main central-station apparatus. Said armature is adapted to be attracted when either of the coils a or a is receiving current, and when so attracted it not only closes upon contact a but upon a second contact a", connected by wire 15 to lamp L and thence by wire 16 to another bus-bar 22. The armature a is fitted with the usual retracting'spring a The second extremity of the winding a is connected by wire 13 to the winding of the magnet N, and thence by wire 14 to a third bus-bar 21. The magnet N is provided with an armature 11, having a retracting-springer, and playing between front and back stops, the front stop a constituting a contact-terminal for circuit 18, which includes the bell Z, the battery Z, and switch V. This circuit is completed through the bell only when the switch is in the position shown, resting upon its contact The second contact '0', however, is provided, upon which the switch may be thrown to cut out the bell.and cut in a branch circuit 1!),c0ntainingalamp-signal L.

I have shown the annuneiator A as provided with a signal-armature a in addition to the relay-armature a. This signal-armature may be omitted, however-,without changing the operation.

It will be understood that the apparatus thus far described is duplicated with the exception of the magnet N and the parts that it controls for every line. The magnet N may be a common relay. It only remains, theret'0re,to describe the office-connecting circuits and the operation of the whole.

For interconnecting the lines at the central station I provide pairs of plugs P and P, having their sleeve and tip contacts respectively connected together by cord conductors 23 24 and 25 2G. Interposed in each cord conductor is a ringing-key K, having springs 75, normally maintaining the continuity of the cord-circuit, but adapted to be spread when the push-button of the key is depressed to disconnect the conductors 25 26 from 23 24 and to connect them to a suitable generator-circuit. In each cord-circuit across the conductors 25 26 I provide a normally-complete bridge 29 30, which includes springs h h of a normally-closed switch having a pushbutton h to open it and the winding of an impedance-coil H, from the middle point of which a conductor 31 is led to a magnet M and thence to battery 13 and ground. The magnet M is provided with a signal-armature m.

The plugs P P, it will be observed, are not similar in their configuration. The plug P has its tip 19 constructed with a thin or annularly-recessed neck, while the plug P has a short thick neck for its tip. The reason for this difierence in the formation of the tips will be apparent upon reading the operation. It is sufficient to say at this point that when the plug P is inserted in a spring-jack its tip will impinge upon a depressed and insulated pro jectio'n j upon the extremity of the spring and cause the latter to leave its twin spring, thereby breaking the circuit 11 12. After the plug P is fully inserted in aspring-jack, however, the projection 7' will rest within the annular recess around the tip, and thereby permit the springs 7' 7' again to come together. Vith the plug P on the other end or, indeed, P which is a trunk-plug connected by conductors 27 28 to the trunk-jack J no such eifect will be produced, the projection j in such case being held down and the springs consequently separated as long as the plug is in the jack.

The operation of my system thus described is as follows: Assuming thatsubscriber X desires to converse with subscriber Y, he operates his generator G while his receiver is still upon the hook. The current produced passes over the line-wire and through the winding a of the annunciator-magnet. This energizes the core, which attracts the armature a and also the signal-armature a", if the latter is used. The following circuit is then immediately closed: from bus-bar 21, forming the terminal of battery B, through wire 14 to magnet N, through wire 13 to winding a on magnet A, through wire 12, spring 7' spring 7' and wire 11 to contact-point a, through armature a and by wire 17 to the bus-bar 20, forming the other terminal of battery B. At the same time another circuit is closed as follows: from bus-bar 22, forming a terminal for battery B, by wire 16 t0 lamp L, by wire 15 to contact-point (1. through armature a and by wire 17 back to bus-bar 20, forming the other terminal for the battery. The closing of the circuit first traced energizes the magnet N and also causes the winding a to reinforce the winding a in its elfect upon the core of the magnet A. Moreover, when the subscriber has ceased operatinghis generator the current flowing through winding a will sufliciently magnetize the core of magnet A to keep the armature a attracted. The line-lamp L will therefore continue to glow or the armature a to be visible, or both, after the generator-current has ceased, while as the magnet N has attracted its armature n the bell Z or the lamp L (this being a pilotlamp for the switchboard-section) will continue to receive current from-the battery Z as long as the circuits remain undisturbed. The operator, perceiving the pilot-lamp and the line-signal, inserts the answering-plug P into the jack J. The tip of the plugin passing over the projection j depresses the same, separating for the moment the springs 7' and This breaks the circuit from battery L through the winding a, and the magnet A, as well as the magnet N, being thereby dedu- IlO ergi'zed the armatures a and h and also the -forth during the connection the springs j and 7' remain in con tact. The operator then receives from the subscriber the number of the line wanted. In doing this she employs listening-in devices of the usual or of any desired type. (Not shown in the drawings.) Finding that the subscribers line wanted terminates upon another board, she inserts the callingplug P into the jack J of a trunk-line leading to the desired board and communicates the number wanted to the operator there stationed over an order-circuit of the usual kind. (Also not shown.) The trunk-operator then picks up the plug P and inserts it in the desired jack J. As soon as she has done so a circuit will be completed from battery Bithrough magnet M, to and through the impedance-coil H by conductors 29 and 25 26 to the plug P by trunk-conductors 27 28, plug P jack J, and the line-wires 1 2 to subscribers station Y, and thence by the conductors 3 and 4, the windings of the ringer Q in parallel, and wire 5 to ground and back to the battery. Current from battery B flowing in this circuit energizes the magnet M, which causes the display of its signal m, thus indicating to the answering operator that the connection is complete, whereupon she depresses the ringing-keyK to send calling-current out over the line to station Y. It will be observed that current cannot flow back from the battery B to the subscribers station X for the reason that as soon as that subscriber has called he has removed his receiver from the hook, allowing the switch S S to rise, thus cutting off the ground 5. The signal m. remains displayed until subscriber'Y answers the call by removing his receiver from the hook. This breaks his ground-circuit,whereupon the retirement of signal an apprises the answering operator of his response and she depresses the key h to separate the springs h and cut oif the impedance-coil and ground branch from the united circuits, thus leaving no grounds upon the circuit in any part.

The trunk-plug P has its tip 19 formed with a short neck, similar to that of the plug P. Consequently when either of these plugs is inserted in the jack of 'a wanted line the springs 1 and 7' will be kept separated as long as the plug is in the jack. The condition of the signals then during the connection is that the circuits of the magnet A of the callingline are completed and ready to respond to generator-current at the close of the conversation, while the magnet A of the called line, with all its dependencies, is disabled for all except momentary signals. Clearing-out signals are therefore received by the answering operator only and by her communicated to the trunk-operator over the order-circuit or in any other desired manner. While this is, however, the preferred method of operating this system, because of the localization of re sponsibility it attains, I do not wish to limit myself, as obviously all the plugs might well be formed, like the plug P, with long thin necks, so that all the line-signals would be capable of responding as clearing-out signals. Supposing that clearing-out current has been sent over the line from both stations to again energize the magnet A and light the lamps L and L, it should be observed that the mere withdrawal of the plug P from the jack will again serve to separate the springs j and 3' and restore all the parts to normal.

In Fig. 2 I have shown a modified form of my invention, wherein the impedance-coil II isdone away with and the calling-plugs have three contacts instead of two, the third contact being connected by wire 31 to lnagnetM and battery B a third contact 7' to cooperate with a third contact on each plug, a connection being thence made by wire 31 to the middle point of the line-winding a on the magnet A. Inasmuch as this winding is permanently bridged across its metallic circuit it obviously takes the place of the impedance-coil. Connection is made from the calling-plugs through thetrunk-lines when trunking is necessary by an extra sleeve 7' in the trunk-jack and a wire 32, leading to the third contact on the trunk-plug.

If during the conversation either subscriber desires to leave his instrument, he allows the same to hang by a suitable cord connecting it with the switch S in the present system is rather important, for if the subscriber X should become tired of waiting and temporarily leave the instrument if he replaced the receiverR upon the hook he would immediately furnish a new ground path for current from battery B and thereby confuse the signal. On the other hand, if he is instructed never to hang up his receiver after once calling until he receives the response he may leave itoff the hook for an indefinite time and so exhaust the local battery.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is

1. In a telephone-exchange system, a sub= scribers line, a switching-terminal therefor, a line-signal having its windings connected to the line and also to a local circuit containing a source of current, said local circuit adapted to be closed when the line-signal magnet is energized, and means made operative upon scribers station, and a central station, and a Each jack is provided with The use of this switch circuit connecting the two and terminating in a spring-jack at the latter; a line-signal magnet having an energizing-winding connected to the line, and another energizing-winding forming part of a local circuit in which is included a source of current, an armature for said signal-magnet adapted to complete said local circuit when attracted, and means made operative by the insertion of a switch-plug in the line-jack to momentarily break said local circuit and permit the retraction of the armature and thereafter to close the break, substantially as described.

3. In a telephone-exchange system, a subscribers station, a central station, and a circuit interconnecting the two and terminating at a spring-jack at the latter; a line-signal magnet having two windings, one permanently connected to the line, and the other included in a local circuit containing a source of current, an armature for the signal-magnet adapted to close said local circuit when itis attracted, and a circuit-breaker operated in making connection with the line to momentarily break said local circuit and thereafter restore the same, substantially as described.

4. In a telephone-exchange system, a subscribers station, a central station, and a circuitinterconneeting the two and terminating in a spring-jack at the latter station, a signalmagnet having two windings, one winding connected to line, and the otherin a local circuit with a source of current; an armature and a contact therefor, for the sign al-magnet, constituting normally open terminals included in the local circuit, andcontact-springs in the spring -jack constituting normallyclosed terminals in said local circuit, and a switch-plug, together with means actuated by said plug for momentarily separating said springs, when it is inserted in the jack, but thereafter permitting them to come together again, substantially as described.

5. In a telephone-exchange system,- a sub-' seribers station, a central station and a circuit interconnecting the two and terminating in connective means at the latter, a line-signal magnet having one winding connected permanently to line, and a second winding included, together with a local alarm or pilotsignal, in a local circuit closed when the linewinding receives current, and means for breaking said local circuit upon making connection with the line, substantially as described.

In testimony whereof I have hereunto set my hand, in the presence of two witnesses, this 16th day of May, A. D. 1899.

\V ILLIAM D. GHARKY.

Witnesses:

F. EARLE VON LEER, ELBERT WILLIAMSON. 

